>
> Which leads me back to the question: Are there different versions of this
> thing, and are some more prone to this failure than others?

Well, I pulled the bad odometer out of my dash pod this morning and
disassembled it (the two I worked on yesterday are my working "spares", plus
I have a broken one for playing with), and lo and behold... the pressed on
pot metal gear on the right was the culprit. It went for the OTHER failure
mode these seem to suffer due to a bad press-fit: the shaft worked its way
leftwards and fell out of the mounting hole. The press-fit metal gear is
apparently the only yhing keeping the shaft in place. Interestingly, I can't
seem to get the pot metal gear to turn on the shaft, but I can make the
shaft slid left-right inside the gear. Now, my other two spare speedo units
have a plastic gear in that position, and those plastic gears are stuck
HARD. On my third "destructive test spare" (with cracked mounting holes) I
was unable to get the plastic gear to budge at all.

So yeah, it looks like there are two different versions. Metal gear, which
comes loose, and plastic gear, which maybe doesn't.
The paint-stamp date on the two plastic gear models are 7.90 and 6.90, the
metal gear one is 3.90. The cast-in date stamps in the plastic housings are
12/89 and 2/90 for the plastic gear models, and 12/89 for the metal gear
one. Either VDO started making 'em with plastic instead of metal sometime
between March and June of '90, or they were a random mix. I don't have any
older ones to check. The metal gear one was the one that came with my '90
from the factory-- and wasn't working when I got it. I "fixed" it the first
time by shoving the axle shaft back into place, but that only lasted
1.5years.  I'm definitely not putting that one back in.

I'll see if I can put some pics up...
-- 
John Bange
'90 Vanagon - "Geldsauger"